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MOX-like crossover and discrete opamp group buy

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#123
tiroth said:
I'm finally satisfied that the boards work. I'd like to (officially) begin accepting payments so we can get these boards made up ASAP.

Go here to pay
http://www.anidian.com/audio/construct/mox_order.shtml

I would like to have all payments made by midnight Saturday, May 8th.

I will plan on sending the order Monday, May 10th. I will continue to post tests, especially for the opamps themselves.

Thanks for all the help from folks who have pitched in so far. I'm certain additional contributions will be made as people squeeze every drop of functionality out of these boards.
Click to expand...

Looks good. I submitted my payment 🙂

--
Brian
 
#124
roddyama said:
Tyler,

Is there a way to insert a "Quantity" column to your order form?
Click to expand...

Rodd,

When you click the Add to Cart it pops up the shopping cart screen, just change the quantity, and click the update button. There is no need for one on the order form. This is the default setup for the paypal shopping cart system.

EDIT: Actually, I guess you do it rather easily by making a text input box for this tag: "<input type="hidden" name="add" value="1">"

--
Brian
 
#126
JensRasmussen said:
I hate to ask this, are all the jumpers set right?

Have you tried another type of cap, or maybe there is a semi short circuit on one of the soldering pads....creating a DC path that would act like a gain offset?
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Definitely not a jumpers problem. I didn't think about it until I was on the bus, but what about the 4k7 to ground hanging off of the discrete opamp? I don't have SPICE at work...
 
#130
The graphs made with NE5532 also have the 4k7 resistors in circuit, they are soldered to the MOX board. I know Fc is not where the peak is, but if you look at the graphs you can see that there is some movement of the expected -3dB point.

I don't think it is a current problem; I think we are at least an order of magnitude under what the opamp is happy to drive.
 
#133
Just bumping this up since it got buried under technical discussions. I am now accepting payments. Especially if you need 2SK389, please get your order in ASAP! Although I will continue to source as many as possible, I've only ordered 100 so far and I will fill requests in the order in which I receive them.

You may order even if you had not previously signed up in the wiki.

Go here to pay
http://www.anidian.com/audio/construct/mox_order.shtml

I would like to have all payments made by midnight Saturday, May 8th.

Thanks again especially to Jens for his hard work, moamps for the design, and BrianGT for his tips on organizing the buy.
 
#135
Re: 2sk389 discontinued?

MBK said:
I called Toshiba Singapore today, the manufacturer, not some retailer. They also say that they discontinued 2sk389. That is a bit troubling. Where do these s2k389 from other retailers come from then? Toshiba also gave me the e-mail of a retailer here who "may have small quantities in stock".
Click to expand...

tiroth said:
Newark says their stock is Panasonic (Matsushita) on their site. Maybe Toshiba just isn't making them in their fabs.
Click to expand...

I just ordered some 2SK389's a month or 2 ago from Newark, and I recall all references being to Toshiba and not Panasonic. The markings on them read "K389" and "BL'3D". I searched a bit but could not identify the maker.
 
#138
Ok. I originally put myself down on the WIKI for some of these but now I'm starting think I might be getting in over my head. These seem to be allitle more complicated that Brian's Gainclone. I want to build some 2 way active crossovers so I can Bi-amp but I' starting to think maybe I need to go with a more complete kit like something from ESP since I've never built an active crossover before. Does anyone know where i can find instructions on how to pick the components I'd need to build these?
 
#139
Kestrel,

Jens has taken the time to create a manual that lists all of the components and the theory behind the design.

http://www.delta-audio.com/Active filter two.htm

Unless you wish to, you need not do any calculations, just stuff the boards with the recommended components.

I've also created a "shopping list" which will be updated soon. This project is definitely more complex than a gainclone, but I think for someone who is relatively inexperienced, the MOX design is superior to a set of fixed crossovers like ESP. The reason I say this is that it is adjustable...you don't need to recalculate and restuff components to try out different curves.
 
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